Subs - Boart Longyear

Subs
Boart Longyear™ RC subs feature precision cut threads that ensure long life and compatibility, and our use of hardened alloys and precision machining maximize drilling economy and increase productivity. For customer convenience, we keep common subs in stock all year long. There are an infinite number of combinations when looking at RC subs—diameter, thread type, configuration, length—the list below is only a representation of popular types we keep in stock. We also make custom subs and provide sub blanks for our customers to machine to their own specifications.
Saver Subs	Adapter Subs	Digout Subs	Cross-over Subs

Blow-down Subs	Blow-up Subs	Tri-cone Subs	Drive Subs

	Saver Subs A saver sub is usually positioned at the top of the rod string, between the first rod and the top drive head assembly, and protects the top drive head threads from the high number of make/breaks during drilling. It is more economical and productive to wear a saver sub versus the threads on the top drive head. Typically, the box thread is the same as the pin thread and standard lengths are 150mm and 300mm (shoulder to shoulder).

	Adapter Subs Adapter subs are used to adapt one size diameter and / or one type of thread to another. custom adapter subs are available - tell us what you need and we will find a solution.

	Digout Subs Positioned between the down hole hammer and the rod string in a pure RC system, a digout sub provides hole stabilization through the pads positioned on the outer diameter while connecting the rod string to the down hole hammer in the event that thread types between the two are different. The outer diameter of the stabilizing pads (or blades) is based on the size of hole being drilled and is typically sized 1/8” smaller than the outer diameter of the bit.

	Cross-over Subs Also referred to as an interchange sub, a cross over sub is positioned between the down hole hammer and the rod string in a conventional RC system. Its primary purpose is to allow an entry point for the sample as it travels from the bit face to the inner tube. In the event that the thread connection between the rod string and the hammer are different, the interchange sub also serves as an adapter sub.

	Blow-down Subs When required, a blow down sub is placed at the top of the rod string once it has been disconnected from the top drive head. It’s used to direct the airflow down the inner tube to clear a sample blockage.

	Blow-up Subs Also known as a blow back sub, a blow up sub is used to direct the airflow up the inner tube (through the head to the sample collection tube) to clear a blockage. When required, it is placed at the top of the rod string once the rod string has been disconnected from the top drive head.

	Tri-Cone Subs A tri-cone sub, also referred to as a roller bit sub, is positioned at the bottom of the rod string in a tri-cone system, connecting the string and the bit. It is available in two configurations: as an adapter sub to connect the rod string to the tri-cone bit in overburden drilling applications (referred to as a tri-cone bit sub) or as a sub with fitted inner tube to allow the sample to be directed up the inner tube to the surface for collection in an exploration system (referred to as a roller bit sub).

	Drive Subs The drive sub is positioned between the head saver sub and the rod string to hold the head wear tube in place. It can also be used as an adapter sub between the top drive head and the saver sub.